Q: I will be installing some type of fireplace, please can you give me some suggestions as to how to provide for the chimney!

A: When I put in the pipe for my wood stove, I used stainless steel "Metalbestos" pipe that is designed for zero clearance situations and is safe to imbed right in the earthbag wall. This same pipe can be used for a fireplace.

Q: I have some discarded rectangular double glazed windows I'd like to use in the structure. Any reason why I couldn't fit a wooden lintel resting on the bags over the top of the window or do window openings have to be arched or triangular?

A: If you can calculate that whatever lintel you use can support the weight of whatever is above it, this would probably work. Arches, circles, and pyramid shaped triangular openings are inherently more stable and more likely to last over time.

Q: I am nervous about plumbing and earthbag walls - Paulina implies it can be done, but her description is fairly brief.

A: I actually used wood framing in the wall between my utility space (with washer and dryer and water heater) and the bathroom, because there was so much plumbing to fit there that it was far easier to do that. On the other hand, you can run water lines in the cracks between bags and even through bag wall (either by leaving larger pipe chases or even pounding the pipe through wall later)...so you can go either way.

Q: Can you put a glass circular skylight to finish a dome structure?

A: I see no reason why a circular glass or plastic dome skylight couldn't be placed at the apex of an earthbag dome, especially if there is a rigid metal frame that can be integrated with the bag structure somehow.

Q: This is a question regarding building an earthbag dome - is there a limit to how many windows you can include in the structure?

A: There are various ways to introduce windows for lighting into earthbag domes. Basically any circular or arched shape can usually be accommodated, including a triangle with one of the corners pointing upward. As long as the windows are well-constructed and integrated into the structure, there is no limit as to how many you have. One way to get a lot of light into a space is to use a glass door of some sort.

Q: When you put your water plumbing into the house from outside, is there some trick that I need to know?

A: I placed mine underground below the frost line to enter the house, and then came up through the floor where I needed it. If frost is not an issue, then it would be possible to just poke the pipe directly through the wall while you are building it, or even pound a section of steel pipe through after the fact.

Q: The climate in Malaysia is hot and humid as we are only a few degrees from the equator. I do wonder about the suitability of the dome shape - especially the roof in this climate. How do we ensure enough ventilation?

A:  I provided ventilation in the earthbag domes that I have built by arranging inlet air vents near ground level, and outlet vents at the very top of the dome. This worked very well, and is easy to do with large diameter pipe (I used inflated tether balls as vent closures). You could feel the air rush by with the convection current!

Q: I have a question on how you installed the cart-wagonwheel as a window in your earthbag house. Did you use a form of some kind and after removed that and installed the wheel? Or did you build around the wheel? The reason I ask is because I have doubts if the wheel has enough width to support the bags that go over the wheel and that still have to harden after tamping.

A: I did not use a form for this, but I was fortunate enough to find some very wide-rimmed old wheels that were able to support the bags directly. With smaller width wheels it might be possible to place a wide steel plate that curved over the top of the wheel to support the upper bags (the sides and bottom are not really a problem for thinner rims).

Q: With the air vents in your papercrete dome, do you close them in the winter and open them in the summer?

A: In general this is true, it depends on the season whether you want the fresh air or not.

Q: Should vent block or concrete or brick infill panels within earthbag be added after the earthbags have been fully built and tamped, and had the roof weight added to it?  I'm wondering about differential settling. 

A: I would say that this depends on the fill material and how well tamped it is. Also, in some circumstances it may be difficult to inserts these elements later. I would think that as long as the fill material is fairly dense and well-compacted, it would be safe to do this as the project is being built, which would likely be easier than later.

Q: I was thinking that tile chimney flue squares would be nice to use for vent openings, but might get cracked when tamping layers above?  I know adding sections of round pipe for little vents like people do would be really strong--don't know how cheap it is overseas.

A: It likely depends on how thick and/or how brittle the flue sections are; some experimentation is in order here. Short sections of plastic pipe are often available as remnants or salvage.

Q: We see Khalili's method uses at times to cut into the surface of the bags to accommodate windows, ventilation pipes and or even doors. I wonder what your experience has been with this when working with "Scoria filled bags".

A: Khalili can get away with this mainly because he only uses hardened adobe in his bags. Loose material would not hold its shape if cut into, and all kinds of problems would likely happen. But even with the adobe, I think this is a poor alternative to carefully planning where openings should be in advance and forming the bag walls around these. He suggested this with his "emergency shelter" where careful planning may not happen.

C: I've been thinking about solar domes made with earthbags, but you need a certain amount of earthbags to maintain wall integrity.  Now I'm contemplating using a series of vaults made with round pipe to create window walls in domes.  They would have to have strong concrete footings and be fabricated in a shop.  I'm estimating 3"-4" pipe covered with sheets of metal.  They could be pre-built, and then the vaults welded together once set in place.  This is an added expense, but it adds solar gain.  It also makes domes more interesting.

R: I made a rather effective earthbag solar dome in both the living room and bedroom in Colorado. Both of the glass doors spanned 6 feet, and provided a lot of solar gain, which along with the large circular windows was just about right for that climate. Those arches were made by using double bags in a cross-hatch pattern...and were very strong, even before being braced with other bags on their sides. The form could have been remove immediately and the arch would have stood. Your pipe idea would probably also work...but may not be necessary.

Q: Can I use square windows? I wanted to use tires, but I would like to have bigger windows.

A: Yes, you can use square windows, but you will need to provide a very strong "lintel" over the top of it to support the weight from above. Probably the easiest way to do this would be with reinforced concrete, which is commonly done in Mexican construction. But there are other ways to make the windows using arches of earthbags, or larger circular-shaped forms rather than tires (which would not be my first choice for this anyway), or even using a triangular shape, with the point going up.

Q: I'm creating some construction notes for a dome and I want to confirm the size and shape of the entry columns.  Your dome guide shows how to do this in detail.  Are the entry columns the same for 3' and 6' wide openings?

A: The buttressing columns were the same for both door sizes. I used the double, cross-hatch pattern of sewn or stapled bags for both. These do take up a lot of space, and while I think they are necessary for the 6' arches, they are probably over-kill for the smaller sizes. The arches themselves over the 6' span were also a continuation of the double cross-hatch pattern, which is astoundingly strong...so I would recommend it for large spans.

Q: Are the arched doorways and windows often seen on domes worth the effort? They are attractive, obviously, but I imagine they take more time to construct (vs a wooden beam for a lintel, for instance). Also, don't they require a bit more carpentry skills for finishing, what with the curved space above the door or window to deal with?

A: (Owen Geiger) There are various ways of building arches.  Yes, the typical method of using fan bags is slow, although I think it's really fun.  Khalili's method of using long tubes of stabilized soil seems really fast.  You could buy tubes just for going over arches.  Wood lintels are less practical, because the dome is round and must support the massive load above it.  And what if termites slowly eat the wood over the years...

Q: My coworkers and I have made a slight change to our building plan as far as the doorway/hallway is concerned. Originally we were going to build a square insert for our hallway then lay a header for support then earthbags on top of that. Now we have decided to create an arch hallway instead. So my question for you is this... when determining the angle of the arch for the hallway, is it better to have a steep or shallow arch? If I have a 7' door, do I start my arch at 7', or can I start it lower?

A: Steeper arches are slightly more stable perhaps, but even half-circle arches are usually fine in openings no wider than about 3 feet. For wider spans, a steeper, more Gothic arch is probably better. Even with a half-circular arch, the first few inches are nearly vertical, so theoretically the arch could be started a bit lower than the height of the door, but I think aesthetically it looks better to start the spring-line of the arch right at the top of the door frame.

Q: Is it best to put the chimney out the top or side? Does the volley ball vent leak?

A: The stove pipes that I have installed were placed near the peak, but they could have gone at the very top. I have generally placed air vent pipes at the peak, and these pipes have a bonnet on the outside which keeps any rain from entering. The tether ball vents have not leaked. In the US you can buy insulated stove pipe that is safe to put right up against the bag material. If something like this is not available you could probably get by with placing cement-stabilized fill in the bags that will touch the pipe.

Q: I was wondering, after reading your account of constructing an earthbag arch, how wide you might make one while retaining stability? The reason I ask is that my husband and I have been considering earthbag building as an option, down the road. Since we are mainly attracted to the lack of lumber involved, attaching a separate roof would defeat this purpose (and add a great deal of expense.) The sticking point that keeps coming up is the construction of a garage, which seems necessary, given the local environment. Would it be possible to safely construct an arched entrance in an earthbag dome wide enough for a car to pass through? 

A: The widest arch span that I have done is 6 ft., and I wouldn't recommend going any wider than this. It might be best to design an earthbag garage with an engineered truss of some sort.

Q: So here's the scene: 14 x 14 earthbag dome, 2-3 feet underground; one arched doorway directly south 36 x 78 inches; arched window`frames directly SE and SW, both 36 x 54 inches; another arched door identical to the first directly west, and two more arched windows, also 36x54 inches, located directly North and East. Should we have to buttress these arched windows and doors, could we buttress inside with built in furniture/shelving. Also, do you see a problem with a skylight at the apex of the dome, should this effect the structural integrity or weaken any cantilevered compression tension happening at the apex.

A: A 14' dome with two doors and four windows will create a lot of openings that will weaken the basic structure of the dome. The 14' dome I made (pictured here) has only one door and two windows at ground level. If you look at the plan for this little dome, you will notice that the door is naturally buttressed by insetting the door frame within the dome and making it vertical to meet the curvature of the dome near the top. The windows were not buttressed, but then they were formed with simple circular culvert couplers inset in the walls, and thus became part of the structure itself. On another dome I did make a kind of interior buttress around an arched, openable window by placing an interior bench below it that helped support long sewn bags up over the arch, placed perpendicular to the wall. There are many other strategies for buttressing door openings pictured on the project pages. You can place a skylight at the apex of the dome if you support it with a strong, rigid framework (or compression ring) that will lock into the bag structure.

Q: I would like to utilize skylighting as much as possible for natural light. I also want to install an exhaust fan to remove heat naturally from the inside. Would you utilize a non motorized exhaust fan or a motorized one. Which would be more of a benefit ? I would hate to force cool air out of the space with a motorized unit.

A: It is a fairly easy matter to place circular skylights at the apex of a dome, and these can be openable to allow ventilation. Another skylight/vent option that doesn't use electicity is shown at http://www.envirosciences.com.au/main/page_home.html The question of the best strategy for venting a structure is complex. I tend to like solutions that have no moving parts if possible. I have never built a wind chimney, but I understand that they work pretty well. There is one built into the dome complex here. On the other hand, to assure that the interior temperature is as consistent as possible, there is definitely more control when you have a powered vent that is thermostatically controlled. Then you would not be sucking out your cool or heat unless you wanted to.

Q: Is it possible to add a room onto an existing earthbag structure and, if so, how would it be accomplished?

A: The best way to add on to an earthbag house is to prepare for that possibility in advance and place a dummy doorway where it might be needed. This way it is a relatively simple matter to plaster over the door until you want to make the addition, and then just knock out the bags in the doorway with no concern about collapsing walls. Otherwise, it might be necessary to carefully brace and provide support for what might be above the doorway (or window) as you remove the bags in the wall.

How would one attach the walls of the new addition to the walls of the structure already in place? I mean, would it be necessary to physically attach them or would it suffice to butt the new wall up against the old one as long as it is tamped and buttressed and the gap sealed properly?

In most cases simply butting the walls against each other would suffice, but to assure that the connection is as cohesive as possible, you could pound rebar stakes into the old wall in such a way that they get embedded in the new one. Also, if you use some bent wire mesh to connect both sides of the two walls before plastering, so that the new plaster tends to bridge the two walls together, this will help.

Q: I saw your information on building a small earthbag home, I couldn't help but wonder how you made the pipe for the stove fit straight up. I am planning on building a small cluster of domes, partially bermed and I want to include a wood stove but thought (until I saw your images) that I would have to make the pipe go out at an angle. Could you tell me how you did it?

A: I situated the stove right at the center of the dome so that the pipe exits at the apex. Otherwise it would likely be necessary to have the pipe exit on an inclined surface of the dome. In either case, you can use a zero-clearance stovepipe, like Metalbestos, that can be embedded right in the earthbag dome.

Q: My husband wants to build the small dome as seen in Mother Earth as a studio for me...this makes me very happy! I would imagine there would have to be some sort of vent for air.

A: I have a vent in my door.  Note the semi-circle that's cut out.  This provides adequate (barely) ventilation for our tool shed, but obviously you'll want more fresh air for your studio.  You can bury plastic pipe for this purpose.  Slope the pipe to prevent water getting in the dome, and screen both ends to keep out pests.  Also, you might want to add glass in the door or even a window.